Improved thermomet



UNITED STATES PATENT OFFICE.

EDVARD A. L. ROBERTS, OF NEV YORK, N. Y.

IMPROVED THERMOMETRICAL' STEAM-GAGE.

Specification forming part of Letters Patent No. 36,3011, dated August 26, 1862.

clare that the following is a full, clear, and` exact description thereof and of its construction and mode or manner of operation, reference being had to the accompanying drawings, and to the letters of reference marked thereon, making a part of this specification.

Figure l is a general view of a complete instrument or gage. Fig. 2 is a representation of an application of such gage so arranged that any given temperature or degree of heat will give an alarm. Fig. 3 is a sectional vicw of the cap B and its construction. The nature or character of my invention y consists in the construction of a metallic thermometrical gage of one or more fusible metals or alloys, and when more than one are used they will be so compounded as to fuse at different temperatures, and in combining therewith a float or standard or their equivalentresting on the surface of such metal, so that as the metal fuses such Weight or standard will descend, and thus give immediate notice of the existing state of temperature or of any change of heat or pressure.

The metal plug or standard A screws into the boiler or other steam-vessel inconnection with which it is to be used, and is hollow, as represented by the dotted lines, so that it will be readily aected by the steam or heat in the boiler. The lower part of it is expanded, as represented, so as to furnish space for the arrangement of the fusible metals and the indicating-rods combined therewith.

In the lower and expanded part of the plug A are made one or more small cavities, c a c a, in which are placed metals or alloys which are compounded to melt or fuse at any required temperature. On the surfaces of such metals rest little pins or wires b b b b, of such weight that as the metal melts they will sink or drop. The position of such wires thus indicates the degree of temperature in tl.; boiler or vessel, the degree of heat at which such alloys will melt being before known.

The quantity of alloy or fusible metal required is very small, as the cavities a a need be but little larger than the pin or standard b b, and, there being but 'little surface of the metals exposed, the loss from oxidation will be very trifling.

By the use ofa device similar to that shown in Fig. 2 the dropping of any one of the wires or standards b and the consequent melting of the fusible metal maybe made to give an alarm, thus calling .attention to the condition or temperature reached; or there may be attached to the standards Z) b a thread connecting with an index-hand moving upon a dial, and in such manner indicating any temperature that may have been reached.

By inclosing this gage in a glass case, or so that it cannot be reached by the engineer, it becomes a perfect and enduring record of any disobedience of orders on the part of the engineer as to not carrying more than a certain head of steam. This is readily effected by having one of the cavities filled with such a metal that it will melt at the temperature a few degrees above that at which the engine may be run. When the pressure exceeds that allowed, the standard will drop and the record of disobedience is made.

In order to guard against explosion of the boiler or steam-vessel, there is placed in the top of the cap B a fusible or metallic or other disk or plate, b, Fig. 3, which will give way at a pressure considerably less than that which the steam-vessel can safely bear. When the pressure reaches such point, the disk will give Way and the steam will escape through the top of the cap B, as shown in Fig. 3. The peculiar arrangement and construction of such cap and disk are not more fully described in this connection, as it may be madethe subject of a special application.

rihe figures l 2 3 4 in Fig. 1 of the draW- Y ings indicate metals fusing at different degrees of heat.

I am aware that fusible alloys have been long used, and sometimes more than one, to

`determine the vtemperature of steanrboilers7 ad that metals have been used to measure fterent degrees of heat, as indicated by their )lor or condition. I do not therefore Claim 1e use of metals or alloys `to indicate differnt degrees of heat; but l What I claim as my/invention, and desire to cure by Letters Patent,` isly A metallic gage consisting of one or moreu lsible metals, in combination-with the indiator or indicators b b, or theirequivalent,'so

aspto indiate-by their position or iiiotiom end either With `or w'ithiifanllarmLthfetemperature `of a. "stealth-vessel; Athe whole\`con strueted substantially as aud for the purposes setfofth A e r g A E. A l'a-OBERTs;"V

Witnesses:

A; I."LONG`, Sg-D: LAW. A 

